The new change try to add a new ComboBox "Category" and pass the value to PODT data engine. This also introduced a new configuration option. But now it makes plasmashell crash without useful error output.

One UI improvement I could see is to allow multi-selection of categories, so for example you could see images from all the nature-related categories but not Car or Sports.

The way I'd envision this working is that instead of a combo box, a label would display the currently selected categories. Next to it would be a button labeled "Change categories" that would use the multi-page KCM API to take the user to another page with a checkbox for each category. This page would allow selecting any assortment of categories, which would then be listed on the main page. It would be sort of like the corner selector UI in the new Notifications KCM.

Anyway, that's definitely a nice-to-have, and this seems fine from a functional and UI perspective already.

One UI improvement I could see is to allow multi-selection of categories, so for example you could see images from all the nature-related categories but not Car or Sports.

The way I'd envision this working is that instead of a combo box, a label would display the currently selected categories. Next to it would be a button labeled "Change categories" that would use the multi-page KCM API to take the user to another page with a checkbox for each category. This page would allow selecting any assortment of categories, which would then be listed on the main page. It would be sort of like the corner selector UI in the new Notifications KCM.

Multi-selection might be difficult to implement in back end. The Unsplash Source API I use only supports a single collection ID. Search API might support multiple keywords, but it is like "AND" logic, not "OR" logic. So for now, I cannot achieve this function.